Actually, by coincidence I cleared out my gym bag today and found it was harbouring the following:

Smelling salts that had gone off.
Wet cardboard (my water bottle had leaked).
Chalk - leaving a trail behind me everywhere.
Wrist wraps
Knee sleeves
Two long-forgotten T shirts
Two towels, in need of a wash
Lifting belt
Some pennies (about 30p in total), covered in chalk
A collection of biros, covered in fluff, none of which worked
A water bottle
A parking sticker and card for my old gym
Lifting shoes
A postcard
About ten receipts for petrol
A sachet of a 'recovery drink' someone gave me as a freebie.